The invention relates to a safety device for selectively track-guided or road-travelling vehicles such as is described in the previously unpublished German Patent Application No. 36 41 708, for example.
In order to be able to monitor the correctly extended state of the sensing rollers during the entry into a track-guided road, and, if necessary to warn the driver in good time, it is proposed in the literature cited initially that a switch actuated by the sensing rollers should be arranged on each of the two transverse guide bars at the start of the track-guided road, which switches, when actuated jointly, switch the optical indicator device to "go". This is, therefore, a road side safetY device, which comes into action upon a change of the vehicle from non-track-guided to track-guided operation.
In the inverse case, namely the change of the vehicle from the track-guided road onto normal public roads, it is likewise of great importance, for reasons of safety, that the sensing rollers are retracted into the rest position. For, particularly when negotiating bends or when approaching stopping places, in the case of sensing rollers still occupying a work position near the ground, collisions with high curb edges may occur, as a result of which the steering mechanism of the vehicle may be damaged. In order to prevent this, in the case of sensing rollers not retractably mounted, predetermined breaking points have been provided in the mounting (German Patent Specification No. 31 03 488) and energy-absorbing catching devices have been connected in parallel in order to retain a broken sensing roller on the vehicle. However, this arrangement is difficult to realize in the case of retractable sensing rollers.
An underlying object of the invention is to provide a safety device for selectively track-guided or road-travelling vehicles with retractable transverse guide rollers which permits a change from track-guided to non-track-guided operation only when the sensing rollers are fully retracted to their rest position.
This object is achieved according to the invention by arranging an optical indicator device beyond the exit point of the track-guided road, providing a vehicle side monitoring device for monitoring the position of the sensing rollers, and providing a signal transmission device for indirectly switching the optical indicator device to a "go" signal only when the sensing rollers are in their rest position. The vehicle side monitoring device monitors the assumption of the rest position by the sensing rollers. When the sensing rollers are located fully in the rest position, the likewise vehicle side signal transmission device, which is coupled to the monitoring device, generates a signal which indirectly switches the optical indicator device arranged behind the exit point of the track-guided road temporarily to "go". On the other hand, if the sensing rollers are still in the work position near the ground, or if they have been transferred only partly towards the rest position, then no signal changing over the optical indicator device is generated by the signal transmission device, and the "stop" signal ahead of the access to the public road system remains.
According to an advantageous development of preferred embodiments of the invention, a signal transmission device may be arranged additionally on the road side, which device, via a likewise additional signal receiving device on the vehicle side, triggers the transfer of the sensing rollers into the rest position after the exit of the vehicle from the track-guided road but before the optical indicator device is reached. By this means, it is possible to execute this sensing roller adjustment in a quite specific route section without action on the part of the vehicle driver. It is thus possible to exclude a premature retraction of the sensing rollers still within the track-guided road due to an operating error on the part of the driver.
To permit the signal transmission between vehicle side and road side parts of the safety device to be realized with the smallest possible structural outlay, the signal transmission may occur wirelessly, for example by means of road side and vehicle side transmission and receiving devices, according to certain preferred embodiments.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.